Annealing box



May 9, 1939. K., .i DEM-u.

ANNEALNG BOX Filed March 16,

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Patented May 9, 1939 UNITED STATES PATENT oFFIcE Pittsburgh Annealing Box Company, Pittsburgh, Pa., a corporation of Pennsylvania` Application March 16, 1938, Serial No. 196,202

1 Claim. (Cl. 263-49) My invention relates to annealing boxes and more particularly to those which have channels or flutes formed `in the walls thereof for stiffening 1 the box walls and at the saine time providing for flexingt-hereohunder temperature changes, with less danger of permanent distortion of the box walls.

In boxes of this type the outermost corners of the channels or corrugations are exposed to great l0 heat, particularly at certain zones extending above the sand seal, and become highly heated before the intermediate portions of the side walls are fully heated. The result is that there is tendency for lexure to be concentrated at such exposed corners, under temperature changes, with consequent cracking of the walls along these convex lines. Furthermore, there is weakening of the metal along these lines, because oxidation occurs there more quickly than in other portions of the box walls.

My invention has for its object the provision of means for reinforcing and protecting annealing boxes along the said lines of earliest failure, thereby increasing the lif-e of the boxes.

Some of the forms which my invention may take are shown in the accompanying drawing wherein Figure 1 is a side view of an annealing box; Fig. 2 is a cross-sectional view of a portion of the box, indicating its position in a furnace; Fig. 3 is a View, on an enlarged scale, taken on th-e line III-III of Fig. 1; Fig. 4 shows a modification of the structure of Fig. 3; Fig. 5 is a fragmentary view similar to Fig. 1, but showing a modification thereof; Fig. Gis a view on an enlarged scale taken on the line VI-VI of Fig. 5, and Fig. '7 shows another modification.

Referring rst to Figures 1 to 3, I show a box B vhaving inwardly projecting chann-els I and outwardly projecting channels 8 formed in the walls thereof. In Fig. 2, the box is shown in position in a furnace or heating chamber 9 and has its lower edge supported in a sand trough IU. A suitable number of heating pipes II are distributed along the walls of the heating chamber in position to effect heating of the box. In some cases, flame burners or other means of fuel consumption are provided in the chamber 9. However, the parts thus far described are known in the art and do not per se constitute a part of the present invention.

The outermost corners I2 of the corrug-ations and the outer faces of the chann-els 8, particularly at the hottest zone of supplied heat, become heated quickly to high temperatures, in advance of the other portions of the box walls, as heretofore indicated. Invorder to protect these exposed corners, and faces from early oxidation and to retard the heating rate thereof relative to other portions of the box walls, I provide metal shields I3 at the sides of the box, it usually being necessary only to protect that portion of the box at the hottest Zone. As shown more clearly in Fig. 3, the shields I3 are of channel form and near their upper and lower ends are provided with bent tongues or flanges I4 that engage with hooks I5 which are welded to the side of the box, the hooks I5 serving to hold the shields in position against the side of the box. The shields may be inserted and removed for replacement by simply sliding them vertically so that their hooks I4 will engage behind the hooks I5, The shields are spot welded at I6 to the sides of the box to prevent their sliding out of eng-agement with the hooks I 5. The shields I3 delay heating of the box walls at the said hottest zones, so that there will be to some extent an equalization of the heating rate and shielding from corrosive atmospheres as between the shielded portions of the box and the other portions thereof, with consequent lessening of distortion and oxidation through heat expansion. Furthermore, there is less ilexure of the exposed corners I2 and oxidation thereof is retarded. The shields I3 are free to expand vertically and laterally relative to the box walls, so that no additional stresses are set up in the walls of the box. To replace worn shields it is necessary only to break the welds I6 and to slide the shields clear of the hooks I5 and then insert new shields.

The invention is of particular utility in connection with boxes formed of sheet metal, but will be useful also in connection with boxes of cast metal.

In Fig. 4 is shown a slightly different form of clips or tongues for releas-ably holding the shields against the box sides, in that the retaining clips 23 and the flanges 24, carried by the box sides and the shields, respectively, are simply of angular form instead of being of hook shape.

Referring now to Figs. 5 and 6, I show the preferred form of my invention, wherein angle plates or strips I8 are employed for protecting the exposed corners of the corrugations, such angles being Welded to the box along their vertical edges. In this form of structure a stiffening channel I9 is disposed peripherally of the box adjacent to its lower edge, in a manner similar to that disclosed in my application Serial No, 139,577, illed April 28, 1937 (now Patent 2,115,416). While the protecting strips I8 are applied only to the projecting corners of the channels instead of over wider areas of the box sides, they nevertheless serve to protect these corners from too rapid heating relative to the other portions of the box sides, protecting them against rapid oxidation and reinforcing or stiffening the same.

The strips I8 are made in short lengths which are slightly spaced at their ends so that they Will have some freedom of expansion and contraction vertically, with less danger of becoming deformed under temperature changes. In those instances where the channel I9 is set at a considerable distance above the lower edge of the box, I provide additional protective strips 2U to the corrugations, below said channel.

The provision of channels in the Walls of annealing boxes gives greater stiffness than do simple corrugations, and lighter gage metal can be used, thus saving in weight and expense. Although in making bends of short radius at the corners of the channels, there sometimes is tendency to weaken the metal at those points, the shields serve to protect and strengthen the corners.

Fig. '7 shows a modification of the structure of Figs. 5 and 6, in that protective strips or shields 2l are held in place by narrow straps 22 welded to the box at points near the ends of the strips. 'I'he strips can be slid into and out of position behind the straps. These straps are preferably formed of heat-resisting alloys so that they will not deteriorate quickly under the action of heat.

While I have shown channels in the box walls, it will be understoodvthat shields, and particularly wide ones as in Figs. 1 to 4, can be utilized to protect the outermost surfaces of ordinary corrugations, Which I may employ instead 0f channels.

I claim as my invention:

An annealing box having inwardly and outwardly projecting channels formed in the walls thereof and extending vertically, and laterallyspaced and vertically extending protective strips overlying the exposed corners of the outwardly projecting channels at those portions of the channels which are subjected to the greatest heat during an annealing operation,the said stripsconforming to the exterior contour of the channels and the webs of the inwardly projecting channels being exposed.

KENNETH J DEAI-IL. 

